Neither Barnaby Joyce nor Matt Canavan will contest the fact they are dual citizens under New Zealand and Italian law, according to the solicitor-general Stephen Donaghue QC.

That means the only issue that will be debated is whether that rules the pair ineligible to sit in Parliament under an interpretation of section 44(1) of Australia's constitution.

The nation's chief counsel also said the Commonwealth is ready to step in and give the High Court legal advice on the citizenship status of the other parliamentarians awaiting a decision on their fate.

But if those other parties, such as One Nation's Malcolm Roberts, do not agree with the advice the Commonwealth gets from lawyers overseas, they can get their own, but risk delaying any judgement on their case.